1. Technical Field
The present invention belongs to the technical field of semiconductor device manufacturing, relates to a method for manufacturing a tunneling field effect transistor, and more especially, to a method for manufacturing a tunneling field effect transistor with a U-shaped channel.
2. Description of Related Art
In recent years, the microelectronic technology with silicon integrated circuits as their core has developed rapidly, and the development of the integrated circuit chip has basically followed Moore's law, namely the integration degree of semiconductor chips increases at a speed of doubling every 18 months. However, with the increase of the integration degree of semiconductor chips, the channel length of MOS transistors is also continuously reducing, and the semiconductor chip performances will decline, or even be unable to work due to the short channel effect when the channel length of the MOS transistor becomes extremely short.
The tunneling field effect transistor is a kind of transistor with an extremely small leakage current, which can further minimize the circuit size and decrease voltage, thus reducing the chip power consumption significantly. By using the tunneling field effect transistor with a U-shaped channel structure, the transistor channel length can be effectively extended, thus further restraining the generation of leakage current in the transistor. Therefore, the tunneling field effect transistor with a U-shaped channel has been widely used. The traditional tunneling field effect transistor with a U-shaped channel is as shown in FIG. 1, wherein the tunneling transistor 10 includes a source region 12, a drain region 13, a substrate region 11 and a stacked gate region composed of a gate dielectric layer 14 and a gate conductive layer 15. The sidewall 16 of the stacked gate region is an insulator of, for example, Si3N4 material, which insulates the conductive gate layer from other conductive layers of the device. The impurity concentration of the substrate 11 is of light doping, the source region 12 and the drain region 13 are of heavy doping, and are of contrary doping types. The insulation layer 17 is the device passivation layer, which isolates the device from other devices and protects the device form the influence of the outside world. The conductive layer 18 is of metallic material and used as the device electrode.
At present, the U-shaped channel of a tunneling field effect transistor is usually realized by forming a silicon oxide film on the provided substrate, then forming a layer of photoresist with a pattern on the silicon oxide film and etching the silicon oxide film and the semiconductor substrate to form a U-shaped device channel. As described above, when manufacturing a U-shape device channel, a layer of photoresist with a pattern will be formed, which will introduce the misalignment of pattern, causing the product manufacturing yield be reduced. In addition, the manufacturing of narrow U-shaped channel is also a difficult point.